This invention relates to a magnetic head control apparatus for controlling the seek operation of the magnetic head in a magnetic disk apparatus.
When a disk drive shifts its head from one to another track; i.e., enters the "seek" mode, it is desirable to shift the head as quickly as possible so as to minimize unproductive time. The actuator has a design force capacity, and this force value is a limiting factor in the amount of acceleration and deceleration which may be applied to the arm assembly which carries the head.
In conventional disk drive servo control systems, a velocity profile is developed which controls motion of an actuator. Such an apparatus is shown in U.S. Pat. No. 4,636,883 to Hashimoto, the teachings of which are herein incorporated by reference. Typically, acceleration occurs at the maximum capability of the drive while the deceleration is governed by a worst case deceleration profile. This profile is developed to cover the worst case conditions of voltage, temperature, actuator torque capability , circuit errors and external shock and vibration. Each drive thus operates under the worst case seek profile regardless of its actual operation conditions or capability.
The present invention is directed at an adaptive velocity profile which maximizes the performance of each drive for each seek to decrease access times for the drive.